Spectral analysis apparatus and spectral analysis method

1. A non-transitory computer-readable recording medium storing a program that causes a computer to execute a procedure to determine a feature of each standard of a wireless environment in which radio signals including a Chirp Spread Spectrum (CSS) signal chirp-modulated co-exist, the procedure comprising: obtaining a spectrum by subjecting each radio signal to fast Fourier transform with predetermined frequency resolution and time resolution capable of visualizing a feature of the CSS signal; coarsening the frequency resolution of the spectrum by adopting an effective value in a specific frequency domain; calculating a duration of the radio signal, based on the coarsened frequency resolution of the spectrum; coarsening the time resolution of the spectrum by adopting an effective value in the duration; calculating a bandwidth of the radio signal, based on the coarsened time resolution of the spectrum; and determining the feature of the radio signal of each standard, based on the duration and the bandwidth.

2. The non-transitory computer-readable recording medium according to claim 1 , wherein the fast Fourier transform is performed with the predetermined frequency resolution and time resolution capable of detecting the CSS signal.

3. The non-transitory computer-readable recording medium according to claim 1 , wherein, when the CSS signal is chirped with a predetermined frequency change rate within a predetermined bandwidth and symbol time width, in each of a case where the frequency resolution is coarsened and a case where the time resolution is coarsened, the frequency resolution and the time resolution are set within an area which is coarser than a feature line coupling the bandwidth on a frequency axis and double the symbol time width on a time axis.

4. The non-transitory computer-readable recording medium according to claim 1 , wherein the feature is that a shape of a spectrum to be visualized is a substantially rectangular pulse area having the duration and the bandwidth, and wherein the procedure: calculates the duration, based on a length of a time axis of the substantially rectangular pulse area when the frequency resolution is coarsened, and calculates the bandwidth, based on a length of a frequency axis of the substantially rectangular pulse area when the time resolution is coarsened.

5. The non-transitory computer-readable recording medium according to claim 1 , wherein, in a case of band where a channel of the radio signal is predetermined, a range in which the frequency resolution is coarsened corresponds to a width of the channel or an integer fraction of the width of the channel.

6. The non-transitory computer-readable recording medium according to claim 1 , wherein the procedure: coarsens the frequency resolution of the spectrum by adopting the effective value in the bandwidth, and calculates the duration of the radio signal, based on the frequency resolution of the spectrum.

7. The non-transitory computer-readable recording medium according to claim 1 , wherein the procedure adopts a maximum value of a detected spectral power as the effective value.

8. The non-transitory computer-readable recording medium according to claim 1 , the procedure further comprising: analyzing a baseband signal of the radio signal by using the determined feature of the radio signal of each standard; and determining bandwidth occupation rate of the radio signal of each standard.

9. A spectral analysis method to determine a feature of each standard of a wireless environment in which radio signals including a Chirp Spread Spectrum (CSS) signal chirp-modulated co-exist, the spectral analysis method comprising: obtaining a spectrum by subjecting each radio signal to fast Fourier transform with predetermined frequency resolution and time resolution capable of visualizing a feature of the CSS signal; coarsening the frequency resolution of the spectrum by adopting an effective value in a specific frequency domain; calculating a duration of the radio signal, based on the coarsened frequency resolution of the spectrum; coarsening the time resolution of the spectrum by adopting an effective value in the duration; calculating a bandwidth of the radio signal, based on the coarsened time resolution of the spectrum; and determining the feature of the radio signal of each standard, based on the duration and the bandwidth, by a processor.

10. A spectral analysis apparatus to determine a feature of each standard of a wireless environment in which radio signals including a Chirp Spread Spectrum (CSS) signal chirp-modulated co-exist, the spectral analysis apparatus comprising: a memory; and a processor coupled to the memory and the processor configured to: obtain a spectrum by subjecting each radio signal to fast Fourier transform with predetermined frequency resolution and time resolution capable of visualizing a feature of the CSS signal; coarsen the frequency resolution of the spectrum by adopting an effective value in a specific frequency domain; calculate a duration of the radio signal, based on the coarsened frequency resolution of the spectrum; coarsen the time resolution of the spectrum by adopting an effective value in the duration; calculate a bandwidth of the radio signal, based on the coarsened time resolution of the spectrum; and determine the feature of the radio signal of each standard, based on the duration and the bandwidth.